The research proposed in this grant application is a direct outgrowth of a neurophysiological investigation conducted since 1968 of the functional organization of the visual cortex in primates. At that time, the work of Hubel and Wiesel and others indicated that a number of extrastriate cortical visual areas existed in the cat, but very little was known about the organization of extrastriate visual cortex in primates. Thus, it seemed desirable to obtain information concerning the existence and visuotopic organization of the extrastriate cortical visual areas as an important first step toward understanding the functional organization of the primate visual cortex. The mapping of the representations of the visual field in visual cortex has been accomplished by determining the receptive fields of single neurons or small clusters of neurons and relating the receptive field positions to recording sites in the cortex. Discovered during the course of this investigation were a series of extrastriate cortical visual areas, each of which is a topographic representation of the visual field and is histologically distinct from surrounding cortex. It is likely that each of these cortical visual areas performs its own distinct set of neural functions, some of which must be unique to each particular area. The proposed research involves (1) examining the quantitative response properties to specific stimuli of single neurons in the extrastriate cortical visual areas in order to determine how information is processed in these areas, and (2) mapping the visuotopic organization of the remaining unmapped regions of extrastriate visual cortex in preparation for subsequent studies of the functional properties of single neurons in these areas. BIBLIOGRAPHIC REFERENCES: Allman, J. M., and J. H. Kaas. The dorsomedial cortical visual area: A third tier area in the occipital lobe of the owl monkey (Aotus trivirgatus). Brain Res. 100: 473-487 (1975). Allman, J. M., and J. H. Kaas. Representation of the visual field on the medial wall of occipital-parietal cortex in the owl monkey. Science 191: 572-575 (1976).